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Integer division: How do you produce a double?
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double num = 5;
That avoids a cast. But you'll find that the cast conversions are well-defined. You don't have to guess, just check the JLS. int to double is a widening conversion. From §5.1.2:
Widening primitive conversions do not
lose informa...
Casting vs using the 'as' keyword in the CLR
When programming interfaces, I've found I'm doing a lot of casting or object type conversion.
18 Answers
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How do I list all the columns in a table?
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For Oracle (PL/SQL)
SELECT column_name
FROM user_tab_cols
WHERE table_name = 'myTableName'
For MySQL
SHOW COLUMNS FROM table_name
share
|
i...
Downcasting shared_ptr to shared_ptr?
...le is like the one in Boost, but it doesn't support shared_polymorphic_downcast (or dynamic_pointer_cast or static_pointer_cast for that matter)!
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How do I remove code duplication between similar const and non-const member functions?
...amp; get() const {
return c;
}
char & get() {
return const_cast<char &>(static_cast<const C &>(*this).get());
}
char c;
};
The two casts and function call may be ugly but it's correct. Meyers has a thorough explanation why.
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'is' versus try cast with null check
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Because there's only one cast. Compare this:
if (myObj.myProp is MyType) // cast #1
{
var myObjRef = (MyType)myObj.myProp; // needs to be cast a second time
// before using it as a MyType
...
}
to t...
Does it make sense to use “as” instead of a cast even if there is no null check? [closed]
.... That sounds like trying to micro-optimize to me. You should use a normal cast when you are sure of the type. Besides generating a more sensible exception, it also fails fast. If you're wrong about your assumption about the type, your program will fail immediately and you'll be able to see the caus...
Difference between is and as keyword
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is
The is operator checks if an object can be cast to a specific type.
Example:
if (someObject is StringBuilder) ...
as
The as operator attempts to cast an object to a specific type, and returns null if it fails.
Example:
StringBuilder b = someObject as StringBuil...
How do you cast a List of supertypes to a List of subtypes?
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Simply casting to List<TestB> almost works; but it doesn't work because you can't cast a generic type of one parameter to another. However, you can cast through an intermediate wildcard type and it will be allowed (since you c...
How do I execute a command and get the output of the command within C++ using POSIX?
...} /* switch (pid = fork())*/
}
You also might want to play around with select() and non-blocking reads.
fd_set readfds;
struct timeval timeout;
timeout.tv_sec = 0; /* Seconds */
timeout.tv_usec = 1000; /* Microseconds */
FD_ZERO(&readfds);
FD_SET(childToParent[READ_FD], &...